Wireless communication systems may be represented in terms of a transmitter 100 and receiver 104, separated by a channel 102, as shown in FIG. 1. The transmitter transforms the data into a signal suitable for transmission over the channel. For the purposes of determining the transmitted data, the goal of the receiver 104 is to remove the effects of the channel distortions from the signal and to obtain an estimate of the data.
The channel 102 represents the effects induced by the environment surrounding the wireless communications system. The channel 102 may distort the transmitted signal in some way. Channel distortions may include amplitude distortions, frequency offsets, phase offsets, Doppler effects, distortions resulting from multipath channels, additive noise or interference.
The receiver 104 may include a channel estimator. The channel estimator may observe a received signal that has been distorted by transmission over the channel 102, and generate a channel estimate based upon this observation. The content of the channel estimate is related to the environment that induced the channel.
Spatial parameters pertaining to the transmitter 100 and/or receiver 104 devices may be known. Such parameters may include spatial coordinates, velocity, and acceleration. For example, the devices may be positioned at known fixed locations. Spatial parameters may also be obtained from a Global Positioning System (GPS) receiver or similar device. Furthermore, spatial information relating to the transmitter 100 may be passed to the receiver 104 within the transmitted data content. An example of such a case occurs in Dedicated Short Range Communications (DSRC) systems, where transmitted data may include position, speed, acceleration and heading information, as described in SAE International, “Dedicated Short Range Communications (DSRC) Message Set Dictionary,” J2735, December 2006.
Reference to any prior art in the specification is not, and should not be taken as, an acknowledgement or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.